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Author: Subject: vacuum pump help
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mad.gif posted on 8-9-2005 at 20:43
vacuum pump help


hello everyone, i have a rotary vane vacuum pump (oilless) that is giving me some trouble. when i turn it on and place my thumb over the tube connected to the vacuum i feel a very strong vacuum. its much stronger than my aspirator, almost painful.

And yet wheni hook it up to my distillation set up water boils at 70 C! that is pathetic it shoudl boil at room temp.

I also tried connecting it to a flask with a rubber stopper and still nothing, its not my glass is definetley the pump.

what could be causing this? is it possible that the pump is not consitentley sucking in air? like creates a strogn vacuum then it dies, etc? i really have no clue ive tried almost everything!
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[*] posted on 9-9-2005 at 02:13


Sounds like it's time to buy a rebuild kit. The vane seals need replacing periodically depending on the use (abuse).
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sad.gif posted on 9-9-2005 at 09:02


vane seal? im sorry i have no clue what that is. ive looked at picture of pumps and at teh top of the rotating part that holds the vanes theres usualy a spring that stops air from flowing from the output into the input. i however do not have oen on mine.

i recentley went out and bought some new vanes for the pump..

ill take a picture of the pump today maybe that will help.
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[*] posted on 12-9-2005 at 02:32


The tip of the vane lobes has a spring loaded seal (carbon/polished steel) that moves along the face of the cylinder. Even a new vane/seal can get wiped out in short order if any grit gets into the pump.

At least any rotary vane I've ever seen.
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smile.gif posted on 18-9-2005 at 19:43
bought a used pump


well i felt that i had wasted enough money on this pump, i could have bought a new one. ill just sell it on ebay or soemthing.

i went ahead and bought a sargent welch 1402 for $50 (no not a typo!) any way the only thing wrong with it is its missing the muffler. im sure these are expensive to replace so i plan on making my own. anyone know where i can find a good diagram of one?
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[*] posted on 19-9-2005 at 12:39


The mist eliminator/muffler is very similar to the ones used on air compressors (not the water separator).

I used an upside down stainless fuel filter. Type with the diptube and screen. Just make sure you oversize it to minimize backpresure.

In a pinch a jar with tissue works.
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